The present invention provides for a method of preparing zeolite A from spent metals-contaminated cracking catalyst. Environmentally acceptable disposal of spent cracking catalyst is a matter of concern to refiners that produce large amounts of spent cracking catalyst each year.
Environmentally acceptable disposal of spent cracking catalyst is an expensive long-range proposition. Because of the high potential for metals leaching from the spent catalyst, hazardous waste landfill sites are generally required for the disposal. This is a costly solution to the disposal problem which requires constant monitoring and which may engender unforeseeable legal difficulties associated with exposure of the hazardous waste to the environment.
Zeolite A is extensively used in household detergents, separation and exchange processes. The present invention solves a potentially undesirable, environmentally difficult disposal problem and provides for the production of a useful zeolite A product.
The art is replete with various catalyst rejuvenation and reactivation processes.
U.S. Pat. No. 4,477,582 (Miale) discloses a process for reactivating a catalyst composition comprising a crystalline zeolite material having a silicon to aluminum atomic ratio of at least 3.5 where the catalyst is deactivated by contact with steam. The subject process involves contacting the steam-deactivated catalyst composition with an aqueous metal salt solution wherein the metal is selected from the group consisting of alkali, alkaline earth and transition metals. This so-contacted catalyst is then contacted with an aqueous ammonium ion solution.
U.S. Pat. No. 4,482,530 (Sanders et al.) discloses a preparation method for the zeolite Y wherein a seed quantity of zeolite Y is mixed with sodium silicate and a relatively small amount of water. This mixture is agitated for up to about 5 hours at ambient temperature. The entire system is then cooled to about -5.degree. C. to 0.degree. C. and sodium aluminate which has been precooled to about 0.degree. C. is added.
U.S. Pat. No. 4,435,516 (Chang et al.) discloses a method for enhancing the activity of a high silica-containing crystalline zeolite having a silica to alumina ratio greater than 500 which involves contacting the zeolite with an ammoniacal solution of an alkali metal aluminate for a period of from 1/2 hour to 5 days at a temperature of from 20.degree. to 50.degree. C. and the pH of at least 10.
U.S. Pat. No. 4,055,482 (Robson) discloses a process for rejuvenating crystalline alumino silicate zeolite-containing catalysts which have become at least partially deactivated through use in a hydrocracking process. In particular, this patent discloses a process for preparing the crystalline alumino silicate zeolite-containing catalysts of substantial activity by treating the used catalysts in a manner such that the residual alkali metal content of the crystalline alumina silicate zeolite-containing catalysts is reduced by about 0.5 weight percent or about 30 percent of the residual alkaline metal originally present. This is accomplished by treating the crystalline alumino silicate zeolite-containing catalysts with certain ion-exchange solutions, such solutions containing hydrogen ion or hydrogen precursor ions easily convertible to hydrogen ions.
U.S. Pat. No. 3,684,738 (Chang) covers a method for reactivating a catalyst deactivated in a hydrocarbon conversion process wherein the catalyst comprises a crystalline alumino silicate zeolite which has a pore size between 5 and 13 angstroms and a silica to aluminum mole ratio of greater than 6 in combination with nickel. The reactivation is carried out without damaging the structural framework of the catalyst and without removing the nickel hydrogenation metal component from the catalyst. This is carried out by burning carbonaceous materials from the surface of the catalyst followed by contacting the catalyst with a 0.1 normal to a 0.5 normal solution of ammonium chloride.
U.S. Pat. No. 3,533,959 (Miale) relates to a process for the reactivation of spent crystalline alumina silicate catalysts with key leaching agents. The disclosed process involves contacting a catalyst comprising a crystalline alumino silicate damaged by exposure to excessive heat or steam containing entrained alumina with a cation-containing agent capable of chelating with aluminum at a pH between about 7 and about 9 where the agent is selected from the group consisting of ammonium salts of ethylene diamine tetracetic acid and diammonium, dihydrogen, ethylene, diamine and tetracetate.
U.S. Pat. No. 4,478,950 (Chu) discloses a process for enhancing the activity of a high silica containing crystalline zeolite material having a silica to alumina ratio greater than 20 which involves contacting the material with a solution containing organic cations selected from the group consisting of tetralkyammonium, cations of alkyamines and mixtures thereof of aluminum ions.
Finally, U.S. Pat. No. 3,493,490 (Plank et al.) discloses a process for the regeneration of alumino silicate catalysts wherein such catalysts are treated with anionic reagents such as liquid water, and a solution containing a hydroxyl ion from a non-alkyl-metal containing compound.